Radial-piston machines



July 5, 19%6 ERDMANN 3,259,074

RADIAL-PISTON MACHINES Filed Feb. 17, 1964 4 Sheets-Sheet 2 ic.4 F |g.3F J 17 IIIII HANS E RDMANN INVENTOR July 5, 1966 ERDMANN 3,259,074

RADIAL-PISTON MACHINES Filed Feb. 17, 1964 4 Sheets-Sheet 6 l J h 32Gb EFig.8 F 9.

HANS ERDMANN INVENTOR.

July 5, 1966 ERDMANN I 3,259,074

RADIAL-PISTON MACHINES Filed Feb. 17, 1964 4 Sheets-Sheet 4 Fig.

HANS E RDMANN INVENTOR.

3,259,074 RADIAL-PISTON MACHINES Hans Erdmanu, Frankfurt am Main,Germany, assignor to Alfred T eves Maschinenund ArmaturenfabrikKornmandit-Gesellschaft, Frankfurt am Main, Germany, a

corporation of Germany Filed Feb. 17, 1964, Ser. No. 345,152 Claimspriority, application Germany, Feb. 16, 1963, T 23,484, T 23,485 12Claims. (Cl. 103174) My present invention relates to radial-pistonmachines and, more particularly, to radial-piston pumps and the likewherein at least one and preferably a plurality of radially reciprocablepistons are operated by an eccentric shaft in order to displace a fluid.

Heretofore, radial-piston pumps of the character described comprisedcylindrical sleeves, which were received in bores provided in a cylinderblock, adapted to house the pistons which were radially reciprocablewithin these sleeves. For the most part, the flow of fluid to and fromthe cylinder bores provided by the sleeves was controlled by means ofslits or other openings formed in the sleeves and co-operating withmeans for selectively admitting fluid to the bores and presentingreverse flow of the fluid. In order to permit the fluid to pass throughthese openings, it was necessary to provide further bores in thecylinder block which were in alignment with the openings in the sleeves.Since exact alignment of the two sets of openings was essential, theproduction of pumps of this nature was relatively costly and timeconsuming. Additionally, such pumps were frequently provided with meanslinking two or more pistons for joint reciprocation, such meansincluding slide blocks co-operating with the pistons so that, when oneof the interconnected pistons is subjected to a compression stroke,another piston or other pistons are engaged in the fluid-chargingstroke. Such slide blocks or glides on the tie rings are costly and theblocks are, moreover, subject to considerable wear and are capable ofgiving rise to many servicing problems.

It is the principal object of the present invention, therefore, toprovide an improved radial-piston machine, such as a pump or motor, ofrelatively simple and inexpensive construction.

A further object of this invention is to provide an improvedradial-piston pump having the characteristics of low wear, ease ofservicing, and all-around high efficiency in operation.

These objects, and others which will become apparent hereinafter, willbe attained, in accordance with the present invention, by providing aradial-piston machine (e.g. a pump adapted to displace a fluid medium ora motor operable by such medium) which comprises a housing having anaxially extending cavity in which generally annular cylinder-block meansis disposed, this cylinderblock means being provided with at least onecircumferential groove and at least one axially extending groove, bothopen in the direction of the housing means, which define with the wallsof this cavity a first channel lying generally in a plane transverse tothe axis of the housing means and cylinder-block means as well as asecond channel spaced from the first channel. fluid-outlet means canthen be provided in either the housing means or the cylinder-block,although preferably in the latter, so as to communicate with theaforementioned grooves and thereby deliver fiuid medium to or remove itfrom the first and second channels. The cylinder-block means can then beprovided with at least two angul-arly spaced, generally radial cylinderbores lying substantially in the plane of the first-mentioned groovewith the cylinder bores communicating with both said channels. Aradially reciprocable piston is then slidably disposed in nited StatesPatent Q Fuid-inlet and isc each of the bores and cooperates with aneccentric shaft rotatable coaxially with the cylinder-block means anddisposed therein for operation by the fluid-pressure differential acrossthe pistons when the machine is a motor and for compressing fluid whenit operates as a pump. The eccentric shaft, which is inforce-transmitting relationship with the pistons, can be rotated by adrive element (e.g. a further shaft) connectable to the eccentric shaftinternally or externally of the housing means.

According to a more specific feature of this invention, each of thepistons is provided with an outwardly open circumferential recess lyingin a respective plane transverse to the respective cylinder bore, two ormore of the pistons being interconnected for joint movement by acoupling ring lying generally in a plane perpendicular to the axis ofthe housing and the cylinder-block and disposed in the axially extendingsecond channel mentioned above; the coupling ring is then received inthe recesses of the pistons interconnected thereby and oscillatesslightly to effect the joint movement of the pistons. It has also beenfound desirable, in some circumstances, to provide two sets of jointlymovable pistons with these circumferential recesses so that two couplingrings, of the character described, can be disposed on axially oppositesides of the pistons for respective engagement with the sets thereof.

I have found that a radial-piston pump of the type referred to above canefficiently include respective unidirectional valve means at thejunction of each cylinder bore with the circumferential channel foradmitting fluid medium from the bores to this channel under the pressureof the pistons. The valve means thus can include a radially movableplate in annular contact with a valve seat formed by the cylinder-blockaround a respective cylinder bore and an annular resilient member, e.g.an endless coil spring, disposed in the peripheral groove in thecylinder block and urging all of the valve plates radially inwardly.

The central cylinder passage of the cylinder-block means can be ofsubstantially uniform cross-section for receiving the eccentric shaftwhich may have an eccentric intermediate portion radially aligned withthe pistons and a pair of bearing portion axially offset from theintermediate portion on opposite sides thereof. These bearing portions,which can be of a diameter proximal to that of the passage, arerotatably mounted in this passage so as to support the eccentric. It hasbeen found that excellent results are obtained when, by virtue of theuniform diameter of the passage, the shaft i axially shiftable in thepassage and the cylinder-block means is provided with an abutment, eg aplate closing one end of the passage, for limiting axial displacement ofthe shaft, resilient means being provided for urging the shaft axiallyinto engagement with the abutment means. To lubricate the contactbetween the shaft and the abutment and to prevent unidirectional loadingof the shaft by hydraulic pressure, a small passage can interconnect theopposite sides of the bearing portion of the shaft engaging the abutmentso as to conduct oil or the fluid medium to a compartment formed betweenthe shaft and the abutment means. The resilient means can be a springbearing axially on the eccentric shaft and urging it away from the dryelement to which the eccentric shaft is connectable. In general, thehousing means should be provided with a wall extending perpendicular toits axis for defining the second channel together with the axiallyextending groove of the cylinder-block means. This wall can be integralwith a sleeve portion of the housing means surrounding the cylinderblock or provided as a separate cover plate removably connectable withthe housing. According to a more specific feature of this invention, thecylinder block can project axially, at least partly, through the plate.The

coupling ring or rings interconnecting the pistons of each set can,moreover, be provided with angularly spaced enlargements received in theannular recesses of the pistons or with angularly spaced projectionsextending transversely to the plane of the ring for engagement with therecesses.

The above and other objects, features and advantages of the presentinvention will become more readily apparent from the followingdescription, reference being made to the accompanying drawing in which:

FIG. 1 is a transverse cross-sectional view through a radial-pistonpump, according to the invention, exposing the interior thereof throughthe fluid-inlet channel;

FIG. 2 is a cross-sectional View taken along the line IIII of FIG. 1;

FIG. 3 is a cross-sectional view taken along the line IIIIII of FIG. 1;

FIG. 4 is a cross-sectional view taken along the line IV-IV of FIG. 2;

FIG. 5 is a view similar to FIG. 4 of a modification of the pump-valvestructure;

FIG. 6 is a cross-sectional view taken along the line VIVI of FIG. 5;

FIG. 7 is a detail-view, drawn to an enlarged scale, of the pistonassembly of the pump of FIGS. 1 and 2;

FIG. 8 is a plan View of a coupling or tie ring adapted to be used inconjunction with the pump of FIGS. 1 and 2;

FIG. 9 is a side-elevational view of another tie ring;

FIG. 10 is an end view of a modified pump with its cover plate removed;and

FIG. 11 is a cross-sectional View taken along the line XI-XI of FIG. 10;

In FIGS. 1 and 2 I show a multiple-piston pump incorporating myinvention. An annular cylinder block 1, having a front face 1' and arear face 1", is receivable in a housing 2 which is open on one side.Block- 1 incorporates an axially extending main passage 3 running fromface 1 to face 1" transversely thereto; another passage aligned withthat in block 1, is provided in housing 2. From an annular groove 4 inthe circumference of block 1 a plurality of cylinder bores 5 (one shown)extend inwardly and intersect bore 3. A shaft 6, having an intermediateeccentric portion 7, is so received within bore 3 that the eccentricportion is rotatably positioned in the chamber 8 created at theintersection of bores 3 and 5 and is coplanar with the pistons. Anaxially extending second groove 9 is provided in the front face 1' ofblock 1 and communicate with fluid-intake 10. Together with housing 2,groove 9 defines a fluid channel 11 which communicates with thecompression manifold 12 via the opening 13, permitting the flow of fluidinto the manifold. A piston 14, having an annular recess 15 below thepiston head 16, is slidably received within the bore 5. A unidirectionalcheck valve 17 rests on annular valve seats 18, 18 along circumferenceof block 1 and is maintained in closed position by a spring 19 which isheld between the ridges 19. A gasket 20 seals the junction of block 1and housing 2 and prevents an escape of fluid. Annular notch 4, togetherwith housing 2, forms a pressure chamber 21 into which valve 17 opens;in turn this pressure chamber communicates with outlet 22 through achannel 23. Bore 3 is closed off at rear face 1" with a cap 24 whichserves the purpose of limiting the axial movement of shaft 6 by theforce of spring 6". Block 1 and housing 2 are joined by a plurality ofscrews 26, sealed with O-rings 26 and the shaft 6, which is supported bybearing portions 27, 27', is provided with a sealing collar 28 againstleakage of fluid. A blind bore 29 in the projecting end of shaft 6 hasaxially extending splines 30 and is adapted to receive a splined driveshaft 6 having complementary serrations to permit relative axialdisplacement of shaft 6. The tie ring 32, finally, is rotatably receivedin the second channnel 9, where it is held against axial movement byretaining ring 31 and serves to couple the pistons of the pump for jointoperation by engaging the annular recesses 15 of pistons 14 (one eachshown) with its formations 320 (see FIGS. 2 and 7).

Upward movement of the piston 14 under the pushing action of eccentric 7causes the fluid present in the corresponding cylinder bore to bedisplaced and to be ejected under pressure through the valve 17 into thepressure chamber 21, from where it travels to the outlet 22. The tiering 32, in its eccentric rotation slides slightly in the pistonrecesses 15 and forces the piston 14 to travel downwardly. The pressurereduction in manifold 12 causes fluid from the conduit 11 to flow intothe manifold through the opening 13 and the process is repeated. It mustbe remembered here, of course, that the pistons are connected for jointmovement by the coupling ring 32.

FIG. 2 illustrates this point more clearly. Four pistons 14 are shown tobe arranged symmetrically within block 1 and to have recesses 15 belowthe heads 16. Eccentric '7 is positioned on shaft 6 and is rotatable ina plane with the pistons longitudinal axes. The tie ring 32 is receivedin groove 9 of the front face 1 and is secured there by retaining ring31. The inner diameter of tie ring 32 is decreased at spaced locationsby the projections 320 (FIG. 7) whose undersides 320' engage therecesses 15. Movement of any given pistons thus will cause slightlyeccentric movement of the tie ring 32 and the resulting travel offormations 320 through the recesses 15 will, in turn, coordinate themovements of the remaining pistons with those of the first. The valve isheld radially inwardly by the endless coil spring 19. FIGS. 5 and 6 showa valve arrangement wherein the plate valve 17a is held resilientlyagainst displacement by undulating band 19a.

FIG. 8 is a detailed view of a ring 32a in an alternate construction.The guide formations 320a in this embodiment are here created by concavedeformation of the ring in the direction of its axis at spacedlocations. Furthermore, unlike the ring shown in FIGS. 2 and 7, thisembodiment comprises only two guide formations 320a and is thereforesuitable for the coordination of two pistons only.

Still another modification of the tie ring is shown in FIG. 9, where theperipheral portions of the ring are bent at spaced locations 32% at anangle substantially transverse to the rings plane and are inclinedtoward its axis.

This construction is particularly useful where it is desirable to havethe body of the ring itself remain outside the piston head recess 15,that is, in cases where different combinations of pistons are to belinked and consequently more than one ring is being used.

In FIG. 7 I show a detail of the piston 14 having its recess 15 belowthe piston head 16. The ring 32 engages recess 15 with guide face 320'of its formation 320 and during its eccentric rotation causes the pistonto oscillate in a rhythm determined by the speed of the ringsoscillation and the number and location of formations 320. Amodification of the pump in FIGS. 1 and 2 is shown in FIGS. 10 and 11.The cylinder block 1 in this case is provided with not one, but twoaxial grooves 9a, 9a in faces 1' and 1", respectively. Two tie rings 32,32' are housed in the channels defined by the respective grooves and areadapted to rotate somewhat therein, as illustrated in FIG. 11. Housing 2is closed on one side by a cap 24 through which flange 54, integral withface 1a of block 1a, projects. The shaft 6a, carrying the eccentric 7a,is adapted for coupling to a drive shaft at the formation 55. Fluidintake 56 and pressure chamber 57 in this modification are partlydefined by the housing 211.

As evident from FIG. 11 the tie rings 32b, 32b in this case are designedeach to control the operation of a respective set of pistons. The ringsshown are those of the embodiment of FIG. 9. It will be understood fromFIGS. 10 and 11 that the guide formations 32017 on both rings may beangularly staggered relative one to another, that is, while ring 32boperates, say, pistons 14a and 14b, ring 32' may actuate pistons 14c and14d. The advantage of this arrangement is the ability to balance thecycle of operation more precisely and to achieve a smoother run. It isclear, of course, that each ring must be so offset from the recesses 9a,9a of the pair of pistons not assigned to it by the angled guideformations 1320b at the points 53, 53' as to prevent the formations3201) from engaging these and from interfering With their properregulation by the other ring. The cylinder block 1a extends axiallythrough the cover plate 24 of housing 2a while the shaft 6a is axiallydisplaced and is held by a spring against the abutment plate 24'. Inboth embodiments an oil-leak passage is provided (711) to lubricate theabutment.

The invention described and illustrated is believed to admit of manymodifications within the ability of persons skilled in the art, all suchmodifications being considered within the spirit and scope of theappended claims.

I claim:

1. A radial-piston machine comprising:

housing means having an axis and provided with an axially extendingcavity;

cylinder-block means received within said cavity and defining with saidhousing means an annular first channel lying generally in a planetransverse to said axis and an axially extending second channel spacedfrom said first channel;

v fluid-inlet means and fluid-outlet means formed in at least one ofsaid cylinder-block means and said housing means, each of saidfluid-inlet means and said fluid-outlet means communicating Witharespective one of said channels;

an eccentric shaft journaled in said cylinder-block means, saidcylinder-block means being provided with at least two angularly spacedgenerally radial cylinder bores lying substantially in said plane andcommunicating with said channels at spaced loca tions along said bores;

a radially reciprocable piston slidably disposed in each of said boresand in force-transmitting relationship with said eccentric shaft; and

respective unidirectional valve means at the junction of each of saidcylinder bores'with said first channel for admitting said fluid mediumfrom said bores to said first channel under the pressure of saidpistons, each of said valve means including a respective valve seatsurrounding each of said bores; a respective radially movable plate inannular contact with said cylinder-block means around the respectivecylinder bore at the respective valve seat, said pump further comprisingan annular resilient member surrounding said cylinder-block means andurging both said plates radially inwardly.

2. A radial-piston pump comprising:

housing means having an axis and provided with an axially extendinggenerally cylindrical cavity;

elongated cylindrical tubular cylinder-block means received Within saidcavity and provided with a pcripheral groove and with an axiallyextending groove at one end of said cylinder-block means, said groovesopening toward said housing means and respectively defining therewith anannular first channel lying generally in a plane transverse to said axisand an axially extending second channel spaced from said first channel;

fluid-inlet means and fiuid-outleet means formed in said cylinder-blockmeans, and communicating with said second and first channels,respectively;

an eccentric shaft journaled in said cylinder-(block means, saidcylinder-block means being provided with at least two angularly spacedgeenrally radial cylinder bores lying substantially in said plane andcommunicating with said channels at spaced locations along said bores;

a radially reciprocable piston slidably disposed in each of said boresand in force-transmitting relationship with said eccentric shaft forreciprocation thereby, said pistons each being provided with anoutwardly open circumferential recess lying in a respective planetransverse to the respective cylinder bore;

a coupling ring lying generally in a plane perpendicular to said axisand disposed in said second channel While being received in both saidrecesses for connecting said pistons for joint movement in said bores;

a pair of axially-spaced annular sealing members hearing upon saidcylinder-block means and said housing means in all-around contact onopposite axial sides of said first channel; and respectiveunidirectional valve means at the junction of each of said cylinderbores with said first channel for admitting said fluid medium from saidbores to said first channel under the pressure of said pistons, each ofsaid valve means including a respective valve seat surrounding each ofsaid bores, a respective radially movable plate in annular contact withsaid cylinderblock means around the respective cylinder bore at therespective valve seat, said pump further comprising an annular resilientmember surrounding said cylinder block means and disposed in saidperipheral groove while urging both said plates radially inwardly.

3. A radial-piston pump as defined in claim 2 Wherein said member is anendless helical spring, said cylinderblock means comprising a pair ofaxially spaced ridges in said peripheral groove maintaining said springin engagement with said plates.

4. A radial-piston pump as defined in claim 2 Wherein saidcylinder-block means is provided with an axially extending centralcylindrical passage of uniform crosssection receiving said shaft, saidshaft comp-rising an eccentric intermediate portion of relatively smalldiameter radially aligned with said pistons and a pair of bearingportions of relatively large diameter axially offset from saidintermediate portion on opposite sides thereof and rotatable in saidpassage while being of a diameter close to that of said passage.

'5. A radial-piston pump as defined in claim 4 wherein said shaft isaxially shiftable in said passage, said cylinderblock means beingprovided with abutment means at one end of said passage for limitingaxial displacement of said shaft, said passage being open axially at itsopposite end, said pump being further provided with resilient meansurging said shaft axially into engagement with said abut ment means.

6. A radial-piston pump as defined in claim 5 wherein said abutmentmeans is a plate received in said passage and said shaft is providedwith an opening at said opposite end of said passage for receiving adrive element, said shaft being formed with engagement means in saidopening for rotatably interconnecting said shaft and said element, saidresilient means including a spring mounted in said opening and bearingaxially upon said element.

7. A radial-piston pump as defined in claim 2 wherein said housing meansincludes a sleeve portion surrounding said cylinder-block means and atleast one annular end plate connected to said sleeve portion anddefining said second channel with said cylinder-block means, said endplate extending perpendicularly to said axis and said cylinder-blockmeans at least partly projecting axially through said end plate.

8. A radial-piston pump as defined in claim 2, further comprising meansfor retaining said ring in said recesses.

9. A radial-piston pump as defined in claim 2 wherein said ring isprovided with angularly spaced enlargements received in said recesses.

10. A radial-piston pump as defined in claim 2 wherein said ring isprovided with angularly spaced portions projecting transversely to theplane of said ring and engaging said recesses.

11. A radial-piston pump comprising:

housing means having an axis and provided with an axially extendinggenerally cylindrical cavity;

elongated cylindrical tubular cylinder-block means received Within saidcavity and provided with a pcripheral groove and With an axiallyextending groove, said grooves opening toward said housing means andrespectively defining therewith an annular first channel lying generallyin a plane transverse to said axis and an axially extending secondchannel spaced from said first channel;

fluid-inlet means and fluid-outlet means formed in said cylinderablockmeans, and communicating with said second and first channels,respectively;

an eccentric shaft journaled in said cylinder-block means, said cylinderblock means being provided with at least two pairs of angularly spacedgenerally radial cylinder bores lying substantially in said plane andcommunicating with said channels at spaced locations along said bores;

a radially reciprocable piston slidably disposed in each of said boresand in force-transmitting relationship with said eccentric shaft forreciprocation thereby, said pistons each being provided with anoutwardly open circumferential recess lying in a respective planetransverse to the respective cylinder bore;

a pair of coupling rings lying generally in respective planesperpendicular to said axis and disposed in said second channel onopposite sides of said bores while being received in both said recessesof the pistons 01 each pair, respectively, for joint movement of eachpair of pistons in said bores;

a pair of axially-spaced annular sealing members hearing upon saidcylinder-block means and said housing means in all-anound contact onopposite axial sides of said first channel; and

respective unidirectional valve means at the junction of each of saidcylinder bores with said first channel for admitting said fluid mediumfrom said bores to said first channel under the pressure of saidpistons, each of said valve means including a respective valve seatsurrounding each of said bores, a respective radially movable plate inannular contact with said cylinder block means around the respectivecylinder bore at the respective valve seat, said pump funt-hercomprising an annullar resilient member surrounding said cylinder-blockmeans and disposed in said peripheral groove while urging both saidplates radially inwardly.

12. A radial-piston machine comprising:

housing means having an axis and provided with an axially extendingcavity;

cylinder block means received within said cavity and defining with saidhousing means an annular first channel lying generally in a planetransverse to said axis and an axially extending second channel spacedfrom said first channel;

fluid-inlet means and fluid-outlet means formed in at least one of saidcylinder-block means and said housing means, each of said fluid-inletmeans and said fluid-outlet means communicating With a respective one ofsaid channels;

an eccentric shaft journaled in said cylinder-block means, said cylinderblock means being provided with at least two angularly spaced generallyradial cylinder lbores lying substantially in said plane andcommunicating with said channels at spaced locations along said bores;

a radially reciprocable piston slidably disposed in each of said boresand in force-transmitting relationship 'with said eccentric shaft, saidcylinder-block means being provided with an axially extendingcylindrical passage of uniform cross-section receiving said shaft, saidshaft comprising an eccentric intermediate portion of relatively smalldiameter radially aligned with said pistons and a pair of bearingportions of relatively large diameter axially offset from saidintermediate portion on opposite sides thereof and rotatable in saidpassage, said shaft being axially shiftable in said passage;

abutment means at one end of said passage for limiting axialdisplacement of said shaft; and

resilient means bearing upon said shaft for urging same axially intoengagement With said abutment means, said coupling ring being providedwith angularly spaced enlargements received in said recesses.

References Cited by the Examiner UNITED STATES PATENTS 2/1949 Raymond103174 1/1958 Christenson 103l74

1. A RADIAL-PISTON MACHINE COMPRISING: HOUSING MEANS HAVING AN AXIS ANDPROVIDED WITH AN AXIALLY EXTENDING CAVITY; CYLINDER-BLOCK MEANS RECEIVEDWITHIN SAID CAVITY AND DEFINING WITH SAID HOUSING MEANS AN ANNULAR FIRSTCHANNEL LYING GENERALLY IN A PLANE TRANSVERSE TO SAID AXIS AND ANAXIALLY EXTENDING SECOND CHANNEL SPACED FROM SAID FIRST CHANNEL;FLUID-INLET MEANS AND FLUID-OUTLET MEANS FORMED IN AT LEAST ONE OF SAIDCYLINDER-BLOCK MEANS AND SAID HOUSING MEANS, EACH OF SAID FLUID-INLETMEANS AND SAID FLUID-OUTLET MEANS COMMUNICATING WITH A RESPECTIVE ONE OFSAID CHANNELS; AN ECCENTRIC SHAFT JOURNALED IN SAID CYLINDER-BLOCKMEANS, SAID CYLINDER-BLOCK MEANS BEING PROVIDED WITH AT LEAST TWOANGULARLY SPACED GENERALLY RADIAL CYLINDERS BORES LYING SUBSTANTIALLY INSAID PLANE AND COMMUNICATING WITH SAID CHANNELS AT SPACED LOCATIONSALONG SAID BORES; A RADIALLY RECIPROCABLE PISTON SLIDABLY DISPOSED INEACH OF SAID BORES AND IN FORCE-TRANSMITTING RELATIONSHIP WITH SAIDECCENTRIC SHAFT; AND